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Genetics
Mendelian genetics and punnett squares
Hardy-Weinberg equilibrium
Inheritance patterns
Independent assortment of genes and linkage
Evolution and natural selection
Down syndrome (Trisomy 21)
Edwards syndrome (Trisomy 18)
Patau syndrome (Trisomy 13)
Fragile X syndrome
Huntington disease
Myotonic dystrophy
Friedreich ataxia
Turner syndrome
Klinefelter syndrome
Prader-Willi syndrome
Angelman syndrome
Beckwith-Wiedemann syndrome
Cri du chat syndrome
Williams syndrome
Alagille syndrome (NORD)
Achondroplasia
Polycystic kidney disease
Familial adenomatous polyposis
Familial hypercholesterolemia
Hereditary spherocytosis
Huntington disease
Li-Fraumeni syndrome
Marfan syndrome
Multiple endocrine neoplasia
Myotonic dystrophy
Neurofibromatosis
Treacher Collins syndrome
Tuberous sclerosis
von Hippel-Lindau disease
Albinism
Polycystic kidney disease
Cystic fibrosis
Friedreich ataxia
Gaucher disease (NORD)
Glycogen storage disease type I
Glycogen storage disease type II (NORD)
Glycogen storage disease type III
Glycogen storage disease type IV
Glycogen storage disease type V
Hemochromatosis
Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)
Krabbe disease
Leukodystrophy
Niemann-Pick disease types A and B (NORD)
Niemann-Pick disease type C
Primary ciliary dyskinesia
Phenylketonuria (NORD)
Sickle cell disease (NORD)
Tay-Sachs disease (NORD)
Alpha-thalassemia
Beta-thalassemia
Wilson disease
Fragile X syndrome
Alport syndrome
X-linked agammaglobulinemia
Fabry disease (NORD)
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
Hemophilia
Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)
Lesch-Nyhan syndrome
Muscular dystrophy
Ornithine transcarbamylase deficiency
Wiskott-Aldrich syndrome
Mitochondrial myopathy
Autosomal trisomies: Pathology review
Muscular dystrophies and mitochondrial myopathies: Pathology review
Miscellaneous genetic disorders: Pathology review
Alport syndrome
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cataracts and p. 554
collagen deficiency in p. 48
inheritance of p. 57
presentation p. 714
Alport syndrome p. 620
Alport syndrome p. 622
Alport syndrome p. 620
Thomas Schmid
Collagens are a family of proteins that are collectively the most abundant protein in the body, and can be found throughout the various connective tissues.
Each member of the family is named with a Roman numeral, and if mutated or absent, can lead to problems in the tissues where that particular collagen is found.
Alport syndrome occurs as a result of mutations in Type IV collagen, which is particularly important in the glomerulus of the kidney, the eye, and the cochlea, and that’s why the symptoms of Alport syndrome are specific to those tissues.
Type IV collagen is a sheet-like structure found in all basement membranes and serves to support cells and form barrier.
The three basement membrane layers are the lamina lucida, lamina densa (where type IV collagen is), and lamina reticularis.
Now within the kidneys, there are glomeruli, which filter the blood and that together with a tubule forms a nephron.
These glomeruli happen to have a basement membranes, called the glomerular basement membrane, or GBM, and that GBM, along with the fenestrated, meaning has pores, capillary endothelium and the podocyte slit diaphragm, forms a selective filter, meaning that water and certain other plasma components can escape the capillary, forming the filtrate that will become urine, but red blood cells and most proteins stay in the glomerular capillary.
In Alport syndrome, kidney function is normal through early childhood, but over time, the missing or nonfunctional type IV collagen causes the GBM to become thin and overly porous.
This allows red blood cells to pass right through from the capillary to the urinary filtrate leading to microscopic hematuria, which is where red blood cells are seen in the urine under a microscope, and this might eventually lead to gross hematuria, where the red blood cells can be seen with the naked eye.
Over time, excessive amounts of protein start to get through the filter, resulting in proteinuria, or protein in the urine.
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